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RSV
Respiratory Syncytial Virus
Sonia Leng
Heather Leonard
Taxonomy
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Order
Family
Subfamily
Genus
Mononegavirales
Paramyzoviridae
Pneumovirinae
Pneumovirus
www.virologyj.com/content/3/1/34/figure/F3
Background Information
of the Virus
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Enveloped virus
150-200 nm
diameter
Helical
nucleocapsid
(-) ssRNA
Most prevalent
during winter
months
www.med.sc.edu
Diseases
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Bronchiolitis
– droplet inhalation through the nose
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Asthma
Pneumonia
COPD
– Chronic Obstructive
Pulmonary Disease
Spread through respiratory secretions
- coughing, sneezing
Infection Process
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RSV envelope fuses to cell membrane
and injects viral genome into the
cell’s cytoplasm where translation will
occur and the virion will be replicated
Genome is transcribed from 3’ end
into monocistronic mRNA molecules
– Each species only encodes a single
protein
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New viruses released via budding
Clumping may occur when new
synthesized RSV surrounded by other
infected cells
New viruses spread from cell to cell
produces a characteristic fusion of
human cells in tissue culture
– the syncytial effect
www.bact.wisc.edu/.../ViralDisease.html
Symptoms
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Occurs within either days or hours of exposure
vary from person to person
symptoms most severe in children under the age of
two
symptoms in adults and children are mild
–
–
–
–
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Stuffy Nose
Nose flaring
Low-grade fever
Wheezing
Rapid Breathing
Ear Infection
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Diagnostic Tests
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For confirmation of RSV,
proper testing of the
patient's respiratory
secretions will:
– Positively identify RSV
– Rule out bacterial
infection
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Nasopharyngeal secretions
containing epithelial cells
are necessary for positive
diagnosis of severe RSV
infections
There are two strains, A
and B
– A causes severe cases
– B is asymptomatic and is
transmitted to most people
http://www.rsvinfo.com/diagnosing/diagnosing.html
Treatment
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Currently no RSV vaccine
available
No treatment given in mild
disease
– just medication to reduce fever
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www.krockathon.com/index.php?module
=rules
Oxygen therapy and mechanical ventilation
(severe disease)
Ribavirin aerosol (severe disease)
– Sometimes used---IGIV (immune globulin intravenous)
with RSV-IGIV (neutralizing RSV antibody) and Ribavirin.
[severe disease]
Treatment (cont.)
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Drug Therapies
1. HRSV IV immune globulin (RSV-IVIG)
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First approved immunoprophylactic
released as Respigam (1996)
made by high titre Sera (protective and neutralizing antibodies)
administered monthly to prevent infection over 4-5 month period.
(during peak season)
2. Palvizumab (Synagis)
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next generation prophylactic
(MAb) humanized monoclonal antibody
IM injection, not IV
admin. During peak season
1960’s- Formalin-inactivated whole-virus hRSV vaccine
given to infants (no previous exposure)
later infected by hRSV, suffered severe symptoms of hRSV.
Prevention
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Frequent hand washing
At-Risk children can be given an injection of RSV antibodies
monthly during peak season.
Keeping school-age children away from younger siblings
(anyone under 2 years of age) if cold symptoms are present
Minimize number of visitors with the infant
Avoid any crowded places
–
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mall, grocery store
If possible, don’t take child to daycare during
RSV season
Partake in influenza vaccinations
www.victorystore.com/.../washhands.htm
Epidemiology
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Transmission
– RSV is easily transmitted via large, aerosolized respiratory
particles, or through contact with nasal secretions, and may even
be transmitted indirectly by contact with contaminated objects,
such as bathroom fixtures or even clothing. The most common
sites of innoculation are the eyes and nose
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Prevalence
– Winter months
– Most frequently transmitted between family members and
hospitals
– The incubation period is three to five days for most patients
– Strain A more prevalent than Strain B
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Global Distribution
– Warmer climates tend to have longer periods of outbreaks
without any peak times
– USA is generally November til May
Latest reports on
morbidity and mortality
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Preventing Respiratory Syncytial Virus Bronchiolitis
– mortality rate in the United States is at 0.13%
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Viral Lower Respiratory Tract Infections in infants and
Young Children
– mortality rate is increased when the child is
immunocompromised.
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Prospective study of healthcare utilization and
respiratory morbidity due to RSV infection in
prematurely born infants
– RSV infection is associated with increased healthcare utilization
and respiratory morbidity in premature babies
– study was performed on infants born before 32 weeks gestation
and during the RSV season of February through September.
Thereafter, they were followed until the corrected age of one.
Latest research on
pathogenicity and prevention
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Pathogenicity
– During the course of RSV infection, predominant T helper cell (TH) 2 response is
associated with disease progression, whereas predominant TH1 reaction provides
response to physical sickness. Interleukin (IL)-18 plays an important role in
adjusting the TH1/TH2 immune response to viral infections. The have tested the
hypothesis that polymorphisms in IL-18 were associated with severe RSV-associated
diseases.
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This study indicates possible involvement of IL-18 in the determination of severe RSVassociated diseases. Defining the genetic basis of RSV bronchiolitis might help us in
identifying new drug targets for a more specific therapy.
Prevention
– Palivizumab is approved for prevention of RSV disease, and ribavirin is approved for
treatment of RSV infections but its efficacy in high-risk patients has not been
conclusively established
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31 (20 male and 11 female) patients hospitalized for RSV infection were treated with
intravenous palivizumab
– from October 2001 through July 2005
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25 patients (80%) also received ribavirin
29 (93.6%) patients survived and 2 died
No adverse events attributed to palivizumab or ribavirin administration were observed.
Treatment of RSV-infected high-risk children with palivizumab alone or in combination with
ribavirin was well tolerated and associated with decreased mortality compared with
previous reports
References
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Respiratory Syncytial Virus. National Center for Infectious Diseases. Respiratory and Enteric Viruses Branch. 2005
http://www.cdc.gov/ncidod/dvrd/revb/respiratory/rsvfeat.htm
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Respiratory Syncytial Virus. KidsHealth. 2006
http://www.kidshealth.org/parent/infections/lung/rsv.html
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Prospective study of healthcare utilisation and respiratory morbidity due to RSV infection in prematurely born infants. S Broughton, A Roberts, G Fox, E Pollina,
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Diminished lung function, RSV infection, and respiratory morbidity in prematurely born infants. S Broughton, R Bhat, A Roberts, M Zuckerman, G Rafferty, and
A Greenough. Arch. Dis. Child. 2006; 91;26-30; 27 Sept 2005
M Zuckerman, S Chaudhry, and A Greenough. Thorax, Dec 2005; 60: 1039 - 1044.
http://thorax.bmj.com/cgi/reprint/61/6/546?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=Broughton&andorexactfulltext=and&searchid=1&FI
RSTINDEX=0&sortspec=relevance&resourcetype=HWCIT
http://adc.bmj.com/cgi/content/full/91/1/26?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&author1=Broughton&andorexactfulltext=and&searchid=1&FI
RSTINDEX=0&sortspec=relevance&resourcetype=HWCIT
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Human Respiratory Syncytial Virus (HRSV). Virology Down Under. Virus, Disease, Diagnosis. 2005
http://www.uq.edu.au/vdu/VDUHumanRespiratorySyncytialVirus.htm
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Signs and Symptoms of Human Respiratory Syncytial Virus. About.com-Lung Diseases. 2006
http://lungdiseases.about.com/od/respiratorysyncytialviru1/a/symptoms_rsv.htm
Respiratory Syncytial Virus Prevention. About.com-Lung Diseases. 2006
http://lungdiseases.about.com/od/respiratorysyncytialviru1/a/rsv_prevention.htm
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Preventing Respiratory Syncytial Virus Bronchiolitis. Mike Sharland and Alison Bedford-Russell BMJ 2001;322:62-63
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http://www.bmj.com/cgi/content/full/322/7278/62?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Preventing+Respiratory+Syncytial+Virus&sea
rchid=1&FIRSTINDEX=0&resourcetype=HWCIT
RSV. The RSV Info Center. http://www.rsvinfo.com/index.html
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Principle and Practices of Clinical Virology. Arie J. Zuckerman. John Wiley and Son Ltd. 2004.
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Viral Lower Respiratory Tract Infections in infants and Young Children. JBM van Woensel, WMC van Aalderen and JLL Kimpen. BMJ 2003;327;36-40
http://books.google.com/books?id=TDEsMa8Jp2EC&pg=PA325&lpg=PA325&dq=global+distribution+of+rsv&source=web&ots=7g69QMY7qd&sig=mIwi7HdAbi
okeSean9JD_C6JOZo#PPA1,M1
http://www.bmj.com/cgi/content/full/327/7405/36?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Viral+Lower+Respiratory+Tract+Infection&se
archid=1&FIRSTINDEX=0&resourcetype=HWCIT
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Interleukin (IL)-18 polymorphism 133C/G is associated with severe respiratory syncytial virus infection. Puthothu B., et al. Center for Pediatrics and
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Intravenous palivizumab and ribavirin combination for respiratory syncytial virus disease in high-risk pediatric patients. Chávez-Bueno S., et al. Department of
Adolescent Medicine, University of Freiburg, Freiburg, Germany. Pediatric Infectious Disease Journal. 2007 Dec;26(12):1094-8.
http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=18043444&ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed
.Pubmed_ResultsPanel.Pubmed_RVDocSum
Pediatrics, Division of Infectious Diseases, The University of Texas Southwestern Medical Center at Dallas, TX. Pediatric Infectious Disease Journal. 2007
Dec;26(12):1089-93.
ttp://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=18043443&ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.
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